GEOG 001 Lecture Notes - Lecture 20: Bulldozer, Basalt, Rhyolite
19 Aug 2020
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Document Summary
Hazards associated with volcanoes take a number of forms but primarily involve the movement of material away from the centre of the volcano and contact with surrounding buildings, crops, and population. Occur when magma reaches the surface and flows out of a central crater or when it erupts from a fissure or vent on the flank of a volcano. 3 major types of lava take their names from the volcanic rocks they form; basalt, andesite, and rhyolite. Lava flows can be fluid and move rapidly; or be viscous and move slowly. Basaltic lavas have low viscosity and high eruptive temperatures havinga velocity of a few km/hr on steep slopes. They harden with a smooth, commonly ropy surface texture called pahoehoe. Cooler, more viscous, basaltic lavas move at a rates of as little as a few metres per day, and harden with a rough, blocky surface texture, termed aa.
